In the process of diffusion what is required for a molecule to move into or out of the cell ?

Active transport. Some particles need to pass through the membrane against the gradient.

Think of it as paddling in a boat. If you are going up river against the current, then you use energy because you have to paddle. So, you are being active.

On the other hand, if you were going down stream, with the current, then you wouldn't have to use energy and there fore, that would be called passive transport

Hope that helps!! :)